Do cybernetics work the same way race skills do? They're not actually 2 perception skill points but two points in perception? Like, if I want to upgrade from 0 to 3, i'd need 4 points, but if I have 2 points bonus, i'd need only 2?

The cybernetic skill bonus is added to you skill "level" so if you have zero strength and get the cybernetic arms installed then your strength is two. But raising your strength to level three only requires one skill point, one more skill point for level four and two additional skill points to reach level five.

Your choice of cybernetic depends entirely on the positive and negative modifiers it gives and your skills. You want one that gives a bonus to a skill that you have that is at level three or less and gives negative modifiers to skills you do not need or use.

This occurs because cybernetic skill bonuses are applied after everything else. If your strength is 0 but you have cybernetic arms (+2 strength), it would still only cost the single skill point to upgrade your strength from 0->1 as Dol Ka stated. The cybernetic +2 bonus would then be applied after that, not affecting the amount of skill points required to upgrade that skill.

I once had "4+2" strength and had apparently wasted 3 SPs on strength 3->4 :(

If race skills worked like that then the races would need to be rebalanced...again. You could look through the cybernetics and list all the ones that would benefit your character build. Then choose one that gives the maximum effectiveness.

That would've been the logical thing to do. And what i was thinking of doing ... But, i'm afraid i don't have a choice. Due to RP reasons, i have to go with hands. My character it seems has four fingers and up until this moment i couldn't explain it. No idea how it will affect my swimming.

If kaminoans can clone people, why cant we just grow body parts? Heck, we are experimenting with that now in our world. Just assume the exceedingly expensive proceedure allows for the ridiculous price of harvesting cloned body parts.